robrwo / net-statsd-lite

A lightweight statsd client that supports multimetric packets

NAME

Net::Statsd::Lite - A lightweight StatsD client that supports multimetric packets

VERSION

version v0.8.0

SYNOPSIS

use Net::Statsd::Lite;

my $stats = Net::Statsd::Lite->new(
  prefix          => 'myapp.',
  autoflush       => 0,
  max_buffer_size => 8192,
);

...

$stats->increment('this.counter');

$stats->set_add( 'this.users', $username ) if $username;

$stats->timing( $run_time * 1000 );

$stats->flush;

DESCRIPTION

This is a small StatsD client that supports the StatsD Metrics Export Specification v0.1.

It supports the following features:

• Multiple metrics can be sent in a single UDP packet.
• It supports the meter and histogram metric types.
• It can extended to support extensions such as tagging.

Note that the specification requires the measured values to be integers no larger than 64-bits, but ideally 53-bits.

The current implementation expects values to be integers, except where specified. But it otherwise does not enforce maximum/minimum values.

ATTRIBUTES

host

The host of the statsd daemon. It defaults to 127.0.0.1.

port

The port that the statsd daemon is listening on. It defaults to 8125.

proto

The network protocol that the statsd daemon is using. It defaults to udp.

prefix

The prefix to prepend to metric names. It defaults to a blank string.

autoflush

A flag indicating whether metrics will be send immediately. It defaults to true.

When it is false, metrics will be saved in a buffer and only sent when the buffer is full, or when the "flush" method is called.

Note that when this is disabled, you will want to flush the buffer regularly at the end of each task (e.g. a website request or job).

Not all StatsD daemons support receiving multiple metrics in a single packet.

max_buffer_size

Specifies the maximum buffer size. It defaults to 512.

METHODS

counter

$stats->counter( $metric, $value, $opts );

This adds the $value to the counter specified by the $metric name.

$opts can be a hash reference with the rate key, or a simple scalar with the $rate.

If a $rate is specified and less than 1, then a sampling rate will be added. $rate must be between 0 and 1.

update

This is an alias for "counter", for compatability with Etsy::StatsD or Net::Statsd::Client.

increment

$stats->increment( $metric, $opts );

This is an alias for

$stats->counter( $metric, 1, $opts );

decrement

$stats->decrement( $metric, $opts );

This is an alias for

$stats->counter( $metric, -1, $opts );

meter

$stats->meter( $metric, $value, $opts );

This is a counter that only accepts positive (increasing) values. It is appropriate for counters that will never decrease (e.g. the number of requests processed.) However, this metric type is not supported by many StatsD daemons.

gauge

$stats->gauge( $metric, $value, $opts );

A gauge can be thought of as a counter that is maintained by the client instead of the daemon, where $value is a positive integer.

However, this also supports gauge increment extensions. If the number is prefixed by a "+", then the gauge is incremented by that amount, and if the number is prefixed by a "-", then the gauge is decremented by that amount.

timing

$stats->timing( $metric, $value, $opts );

This logs a "timing" in milliseconds, so that statistics about the metric can be gathered. The $value must be positive number, although the specification recommends that integers be used.

In actually, any values can be logged, and this is often used as a generic histogram for non-timing values (especially since many StatsD daemons do not support the "histogram" metric type).

$opts can be a hash reference with a rate key, or a simple scalar with the $rate.

If a $rate is specified and less than 1, then a sampling rate will be added. $rate must be between 0 and 1. Note that sampling rates for timings may not be supported by all statsd servers.

timing_ms

This is an alias for "timing", for compatability with Net::Statsd::Client.

histogram

$stats->histogram( $metric, $value, $opts );

This logs a value so that statistics about the metric can be gathered. The $value must be a positive number, although the specification recommends that integers be used.

This metric type is not supported by many StatsD daemons. You can use "timing" for the same effect.

set_add

$stats->set_add( $metric, $string, $opts );

This adds the the $string to a set, for logging the number of unique things, e.g. IP addresses or usernames.

record_metric

This is an internal method for sending the data to the server.

$stats->record_metric( $suffix, $metric, $value, $opts );

This was renamed and documented in v0.5.0 to simplify subclassing that supports extensions to statsd, such as tagging.

See the discussion of tagging extensions below.

flush

This sends the buffer to the "host" and empties the buffer, if there is any data in the buffer.

STRICT MODE

If this module is first loaded in STRICT mode, then the values and rate arguments will be checked that they are the correct type.

See Devel::StrictMode for more information.

TAGGING EXTENSIONS

This class does not support tagging out-of-the box. But tagging can be added easily to a subclass, for example, DogStatsd or CloudWatch tagging can be added using something like

use Moo 1.000000;
extends 'Net::Statsd::Lite';

around record_metric => sub {
    my ( $next, $self, $suffix, $metric, $value, $opts ) = @_;

    if ( my $tags = $opts->{tags} ) {
        $suffix .= "|#" . join ",", map { s/|//g; $_ } @$tags;
    }

    $self->$next( $suffix, $metric, $value, $opts );
};

SUPPORT FOR OLDER PERL VERSIONS

Since v0.8.0, the this module requires Perl v5.20 or later.

Future releases may only support Perl versions released in the last ten years.

SEE ALSO

This module was forked from Net::Statsd::Tiny.

https://github.com/statsd/statsd/blob/master/docs/metric_types.md

https://github.com/b/statsd_spec

SOURCE

The development version is on github at https://github.com/robrwo/Net-Statsd-Lite and may be cloned from git://github.com/robrwo/Net-Statsd-Lite.git

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/robrwo/Net-Statsd-Lite/issues

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR

Robert Rothenberg [email protected]

The initial development of this module was sponsored by Science Photo Library https://www.sciencephoto.com.

CONTRIBUTORS

• Michael R. Davis [email protected]
• Toby Inkster [email protected]

COPYRIGHT AND LICENSE

This software is Copyright (c) 2018-2024 by Robert Rothenberg.

This is free software, licensed under:

The Artistic License 2.0 (GPL Compatible)

net-statsd-lite's Issues

[Documentation] Change ABSTRACT

It's not clear if "lightweight" is still applicable, since it has a several non-core prerequisites.

Problems with inlined type constraints

The PosInt type, for example, is defined this way:

declare "PosInt", as Int,
  where { $_ >= 0 },
  inline_as { my $n = $_[1]; "$n >= 0" };

However, inline_as blocks are expected to also check the value validates against the parent constraint. So your check is just comparing $n against 0. It's not checking that $n is an integer.

perl -MNet::Statsd::Lite::Types=PosInt -E'say PosInt->compiled_check->(1.1)'

The above prints 1 (true). So the value 1.1 is accepted as a positive integer, because you're not checking the value is an integer.

This feature of the inlining API is inherited from Moose, which Type::Tiny aims to mimic. And it does make sense if you want to build very efficient inlined type checks. HashRef inherits from Ref which inherits from Defined. So you could end up with checks like:

defined($val) and ref($val) and ref($val) eq 'HASH'

If the inline_as block can short-circuit the parent checks, we can short-circuit checking definedness and checking ref twice, and it can be inlined as just:

ref($val) eq 'HASH'.

But in your case, you don't want PosInt to short-circuit the Int check. So:

declare "PosInt", as Int,
  where { $_ >= 0 },
  inline_as { my $n = $_[1]; sprintf("%s and %s >= 0", Int->inline_check($n), $n) };

Because this is a pretty common pattern, there's a shortcut for it. If you return a list, they are joined together with and, and if the first item on that list is undef, the parent type check will be used.

declare "PosInt", as Int,
  where { $_ >= 0 },
  inline_as { my $n = $_[1]; (undef, "$n >= 0") };